Kaz

396 reputation

bio	website	kylheku.com
	location	Vancouver, Canada
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Check out the TXR language http://www.nongnu.org/txr

	396 reputation	bio	website	kylheku.com	visits	member for	1 year
16 badges		location	Vancouver, Canada		seen	1 hour ago

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1h	comment	Why is a degree Celsius exactly the same as a Kelvin? @dexter Can you accept this correct answer which gives both the current dependency of the Kelvin on the degree celsius, as well as the historic one?
May 22	comment	Quantum mechanics and everyday nature Although a bipoloar junction transistor may require the tunnel effect to work, it is accurately described by the Ebers-Moll equations that do not make a direct reference to quantum mechanics. At some level, everything requires quantum mechanics in order to work, even a 100 kilogram mass oscillating on a big steel spring.
May 22	comment	Quantum mechanics and everyday nature By this logic, the naked eye phenomenon of gravity also requires quantum mechanics because the classical framework only gives us non-explanatory cruft like $\frac{gmM}{r^2}$, and doesn't explain why there is gravity associated with mass.
May 17	comment	How can I determine whether the mass of an object is evenly distributed? If you cannot tell any external difference between the black box object and a white box object of the same shape whose mass is evenly distributed, or at least no relevant difference, then can't it be concluded that the mass of the black box is evenly distributed?
May 11	comment	Why Won't a Tight Cable Ever Be Fully Straight? This is false. At the minimum height point, there is an infinitesimal slice of the cable which is horizontal. What's holding up every little infinitesimal slice of a cable which has nonzero thickness is not only tension, but sheer stress.
May 5	comment	Why isn't temperature measured in Joules? @Johannes Not any more that I would say that it's incorrect to write that "the number of centimeters is 42". :)
May 1	comment	Showing that position times momentum and energy times time have the same dimensions You have to be careful not to run into multiplication that is really something else in disguise, like a cross product. For instance, informally, "force times distance" could refer to torque (force at an angle, with distance representing displacement from the point of rotation or fulcrum) or "force times distance" could be work (pushing against a resistance, resulting in a displacement across a distance). In the imperial system, foot-pounds is work, but pound-feet are torque. :)
May 1	comment	Does the unit of a quantity change if you take square root of it? Why you sometimes see plots with funny units is that they are useful. For instance, log or log-log graphs: logarithmic frequency, versus decibels. If the given distance actually varies with the square root of mass, then this square root of mass plot will reveal that by showing a straight line. Plus any deviations from that straight line fit will be more clear.
May 1	comment	Does the unit of a quantity change if you take square root of it? What does the square of speed of light represent in $E = mc^2$? Or the square of velocity in the above $\frac{1}{2}mv^2$? It means that energy goes up with the square of speed, that is all. You tell me where the square root of mass comes up and I will come up with an interpretation.
Apr 29	comment	How can Ohm's law be correct if superconductors have 0 resistivity And that on resistance region behaves as a real resistance, for instance to an AC signal, which only cares about the changes in current w.r.t. changes in voltage. Another exammple is the input impedance of an amplifier which has a bias current flowing out of it. You can't just do R = V/I. Rather you might divide the peak-to-peak voltage of an applied signal by the peak-to-peak current variation.
Apr 16	comment	Why does my bicycle brakes squeak in the morning? This question is anecdotal. It is not universally observed that bicycle brakes vibrate or squeak in the morning. Temperature effects could be at play here. Also, surface quality change: suppose that when the bike is not in use overnight, the oxidation layer on the rim thickens by a few angstroms, but is then literally erased by the brake pads. Perhaps, also, the rubber debris which sticks to the rim undergoes some change when it is undisturbed for some hours.
Apr 16	comment	Workdone in an equipotential surface is zero? An equipotential surface is one in which all the points have the same potential. Not necessarily electric, I think. It could be, say, gravitational.
Apr 15	comment	What makes running so much less energy-efficient than bicycling? Agree with Steven Roose. High gears only waste
Apr 15	comment	What makes running so much less energy-efficient than bicycling? You're working against gravity in a wasteful way: not like an elastic bouncy ball which stores energy and comes back to almost the same height, but more like a sack of rice.
Apr 15	comment	What makes running so much less energy-efficient than bicycling? I don't think you understand kinetic energy. You do not have to continuously supply energy to an object to maintain its kinetic energy (except to replace what is lost by drag or friction).
Apr 12	comment	Why isn't temperature measured in Joules? So if I write the number 42, and not put any units, you understand that it's 42 degrees of freedom, and not 42 Hertz or 42 dollars?
Apr 12	comment	Why isn't temperature measured in Joules? I get the point. Likwise pressure can be measured in Newtons instead of Pascals (because we can assume some unit area), and so on. Come to think of it, people sometimes say "fifteen pounds of pressure" and neglect the square inch.
Apr 12	comment	Why isn't temperature measured in Joules? @SteveB Sure, just like you can measure mass in pounds, even though it's unit of force, akin to Newtons.
Apr 12	comment	Why isn't temperature measured in Joules? "degrees of freedom" is a unit, like "widgets" or "dollars".
Apr 12	comment	Why isn't temperature measured in Joules? The average of a unit cannot be expressed in the same units, if the average is actually a density measure! The average mass of a sack of potatoes is still measured in kilograms, right? But density is also a kind of "average" mass: the average mass of a unit of volume. And that cannot be measured in kilograms any more, because then we have to assume a hidden volume unit, which will then be terribly misleading in all the calculations involving density. The arithmetic of units will no longer follow the manipulations of formulas.